1. Field of the Invention
The present invention relates to semiconductor devices and, more particularly, to a semiconductor device which is most suitable for realizing a microminiature functional electronic component used for portable telephones, personal digital assistants and the like.
2. Description of the Related Art
Recently, information apparatuses such as PHS's and PDA's (personal digital assistants) are widely used. There is a significant demand for the reduction of the size of such information apparatuses.
In order to satisfy such a demand for reduced sizes, efforts have been made to reduce the size of electronic circuit components as mush as possible.
For example, as a resonance circuit required for the transmission and reception of signals, as shown in FIG. 6, an integrated circuit 31 including capacitance is formed on an upper surface of a semiconductor device 3 constituted by a semiconductor wafer chip W3, and externally attached inductance, i.e., a coil 30, is connected to the integrated circuit 31.
However, the most significant factor that has hindered the reduction of size in configuring conventional compact communication apparatuses is the presence of a coil 30 as described above that is required for configuring a resonance circuit for transmission and reception of signals.
An electronic circuit and capacitance can be easily realized on the same surface of a semiconductor wafer chip. However, it is not a so preferable solution to form inductance on the same surface.
For example, as shown in FIG. 5, it is possible to form inductance 42 in the form of a planar coil on a wafer chip of a semiconductor device 4. However, an attempt to maintain a sufficient coil diameter and number of turns to increase the capacity of the inductance will result in an increase in the area on the wafer chip occupied by the inductance. The resultant need for increasing the surface area of the wafer chip also goes against the efforts toward compactness.
Since it is not so advantageous to form inductance on a surface of a wafer chip as described above, a coil 30 has been externally attached.
Such externally attached inductance is a significant factor that has hindered the realization of microminiature information apparatuses.
Further, the use of externally attached inductance has been a cause of cost increase also in point of the number of parts and the number of man-hour for assembly.